Abstract:
In the present study, Temperature, Dissolved Oxygen (DO) and Biochemical Oxygen Demand (BOD) were monitored in the Mansar and Renuka lakes located in the Western Himalayan Region. The results have shown that DO profiles seem to mimic the trend of thermal profiles under the same periods. Further, stratification of the lake during summer and mixing condition during winter months is clearly visible. DO and BOD values indicated that bottom layers of these lakes remain mostly under anoxious condition (DO < 6.0 mg/I) throughout the year. Based on thermal behavior, both these lakes could be classified under monomictic type of lakes having one overturn of water in a year.
Low temperature from top to bottom coupled with DO below 4.0 mg/I, may also be a reason for frequent fish mortality in these lakes reported during v.inter months. In view of DO deficit, suitable artificial measures are required to keep adequate DO levels for maintaining ecological balance in the system.
